Broken (pjo & HP)

Need Ideas

Idk what to do with the story
Ik that they are all going to be in grydfindor but like I'm not sure how to make the book not drag on
- Lupin is going to be the DADA teacher
- Percy is going to face a boggart at some point
- Harry is going to find a photo album of everyone and make comments about Annabeth
- Ron is going to find out about the demigods
Comment what you think about these ideas and I'm not sure should I count the triwizard tournament as
Beauxbatons
Durmstrang
Hogwarts
And whatever school the demigods are from and have 4 competitors or just do 3?
Give me any other ideas to make the story interesting I will take any and most likely put them in the story and credit you with them.